In some applications it may be desirable to compare a difference in either one or both of a phase and an amplitude of two RF signals. For example, the above referenced related applications discuss various circuits for detecting difference in operating characteristics of a main circuit by using a replica circuit as a reference. A sensed difference in operating characteristics of the two circuits can then be used to drive a tuning control circuit to minimize the sensed difference. In some cases, the operating characteristics may influence amplitude and/or phase of an RF signal processed by the main circuit, and therefore the sensed difference can be based on a difference in amplitude and/or phase of the RF signal processed by the main circuit and an RF signal processed by the reference replica circuit.
A person skilled in the art would realize that performance of the tuning control circuit in terms of reaction time to a detuned main circuit is affected by a sensing time of the sensed difference. Furthermore, since the operating characteristics of the main circuit are measured as a difference with respect to ones of the reference replica circuit, sensing of the operating characteristics may be performed without requirement for complex calibration (e.g., as would be required for sensing an absolute value of an operating characteristic) of the sensing circuit.
It follows that in such application where a difference in either one or both of the phase and amplitude of two RF signals (of main and reference circuits) is required, a simple, low power, small size, and fast differential amplitude and/or phase detection circuit may be used. A motivation for the teachings according to the present disclosure is to provide such circuit.